SUMMARYPollen grains from four pollen source genotypes (H55, Oh43, K64 × K55, Ky49 × Ky27) were cultured on an artificial medium (15% sucrose, 0.6% bacto‐agar, 0.03% calcium nitrate, 0.01% boric acid) supplemented with four concentrations (0, 5, 25, 100 ppm) of gibberellin A3(GA3). At 1, 2, and 3 h after inoculation, germination percent and pollen tube length were measured. A highly significant concentration x pollen source genotype interaction for germination percent was obtained. Depending on the pollen source genotype, increasing GA3concentrations either substantially increased or did not alter germination percent. For pollen tube length, a highly significant concentration x pollen source genotype interaction was also obtained. However, depending on the pollen source genotype, increasing GA3concentrations either increased, decreased, or had no effect on pollen tube length. Any stimulatory effect of GA3on pollen tube length was expressed early in the germination process or between inoculation and one h after inoculation. The results suggested that heterozygosity level could be a contributing factor in the GA3response and within each pollen source genotype, the effects of GA3on germination percent and pollen tube length were independ